How to determine the backing host physical memory for a given guest ?

[Chegu Vinod <chegu_vinod@hp.com>]

Hello,

On an 8 socket Westmere host I am attempting to run a single guest and 
characterize the virtualization overhead for a system intensive 
workload (AIM7-high_systime) as the size of the guest scales (10way/64G, 
20way/128G, ... 80way/512G). 

To do some comparisons between the native vs. guest runs. I have 
been using "numactl" to control the cpu node & memory node bindings for 
the qemu instance.  For larger guest sizes I end up binding across multiple 
localities. for e.g. a 40 way guest :

numactl --cpunodebind=0,1,2,3  --membind=0,1,2,3  \
qemu-system-x86_64 -smp 40 -m 262144 \
<....>

I understand that actual mappings from a guest virtual address to host physical 
address could change. 

Is there a way to determine [at a given instant] which host's NUMA node is 
providing the backing physical memory for the active guest's kernel and 
also for the the apps actively running in the guest ? 

Guessing that there is a better way (some tool available?) than just
diff'ng the per node memory usage...from the before and after output of 
"numactl --hardware" on the host.

Thanks
Vinod